1. Field of the Invention
The present invention relates generally to protective devices for trailer tow rings, and more particularly, to improved devices for deterring theft of a trailer.
2. Description of the Prior Art
It is customary for heavy flatbed trailers used for transporting heavy construction equipment such as bulldozers and the like to employ a ring hitch at their forward ends to which a traction vehicle can be readily attached and detached. A construction which is generally representative of the Prior Art is disclosed in the U.S. patent to Schoneberg, U.S. Pat. No. 2,835,510 issued May 20, 1958. That patent discloses a draw bar hitch which is reasonably well secured against accidental or unintended separation of the tractor and the implement to be drawn, but does not provide protection against their intentional separation. Indeed, the cited patent did not concern itself with such intentional separation of the driving and the driven elements.
Other patents disclose allegedly theft deterrent trailer hitch lock devices for use with trailer hitches of the type employing a ball and socket construction. The patents to Vuillemot, U.S. Pat. No. 3,884,055 issued May 20, 1975 and to Allen et al., U.S. Pat No. 4,032,171 issued June 28, 1977 are representative of such constructions. However, in each instance, the construction disclosed provides for security in the form of a padlock which is fully exposed. By reason of such exposure, a thief or unauthorized person would encounter a minimum of difficulty to remove the padlock in that the shank of the padlock could be easily cut or the body of the padlock smashed away from the shank. Such activity would thereby eliminate the benefits of the inventions as disclosed in those patents.
Apparently to provide for added protection against the elements and against vandals, constructions such as those disclosed in the patents to Hudson, U.S. Pat. No. 3,844,143 issued Oct. 29, 1974 and to Bulle, U.S. Pat. No. 4,186,575 issued Feb. 5, 1980 disclosed devices which the inventor, in each instance, claims to be effective in preventing theft of trailers employing a tow ring. Although the locking mechanisms in both instances are protected to a greater degree than in the constructions disclosed in the patents, they appear to be fragile, can be adversely affected by the weather, and are somewhat complex in their construction.
With proper deference being given the aforesaid patents, each of which, on its face, disclosed advances in the state-of-the-art of the construction of tow hitches and protective devices therefor, when each respective patent was granted, nonetheless, the present invention is deemed to be a considerable improvement over such known devices. Indeed, it was with recognition of the need and of the state of the prior art that the present invention was conceived and has now been reduced to practice.